For effective fire prevention and fire fighting, polymer additives with thickening properties are applied for increasing the viscosity of the fire extinguishing water in order to attain improved adhesion, as compared to just water, of the fire extinguishing medium to the surfaces, in particular on sloped surfaces.
Known from patent EP 0 774 279 B1 are viscosity increasing water additives which exhibit low moieties of acrylamido-propane sulfonic acid (AMPS). However, these polymers are not suitable for common salt containing aqueous solutions.
The U.S. Pat. No. 5,274,018 patent describes how soluble salts such as sodium chloride interfere with the swelling ability of polymers. Such interference frequently occurs when using water absorbing polymer gels in medical, chemical and agricultural applications. The swelling ability of the described polymer gels results from the electrostatic repulsion of the charges on the polymer chains and from the osmotic pressure of the counter ions. The swelling ability of such polymers is drastically reduced in a saline solution. Solute salts such as sodium chloride exert two types of effects on ionic polymer gels. They shield off the polymer charges and balance out the osmotic imbalance by the presence of counter ions inside and outside of the gel matrix. The loose ions thereby undesirably transform the ionic gel into a non-swellable, non-ionic gel. In this document, the problem of the saline content is solved by adding ionic surface active substances to the polymer surface. However, such surface active substances are unsuitable for industrial scale production and therefore do not qualify as volumetric goods for fire prevention and fire fighting.